At the beginning of the 20^(th)century,German scientist Richard Semon introduced the term'engram'to describe the neural substrate implicated in the processes of memory formation and retrieval[1].The trace of t...At the beginning of the 20^(th)century,German scientist Richard Semon introduced the term'engram'to describe the neural substrate implicated in the processes of memory formation and retrieval[1].The trace of the corresponding biophysical and biochemical changes in the brain responding to an external stimulus is called an engram,and understanding the physical manifestations of memory formation and recall remains a fundamental yet unresolved question[2].展开更多
The effect of hot extrusion and addition of Y element on the corrosion behavior of MgeY alloy was investigated by weight loss,immersion tests and potentiodynamic polarization measurements.The results showed that the g...The effect of hot extrusion and addition of Y element on the corrosion behavior of MgeY alloy was investigated by weight loss,immersion tests and potentiodynamic polarization measurements.The results showed that the grains became finer and uniform by increasing Y element,after extrusion.The corrosion resistance of MgeY alloy after extrusion was deteriorated with the addition of Y element and corrosion rates decreased in the following order:Mge13.78Y>Mge7.46Y>Mge5.23Y.展开更多
[Objectives]This study was conducted to screen best process parameters for making Foshou yam and honey can.[Methods]The Foshou yam produced from Wuxue was used as a raw material to prepare Foshou yam and honey nutriti...[Objectives]This study was conducted to screen best process parameters for making Foshou yam and honey can.[Methods]The Foshou yam produced from Wuxue was used as a raw material to prepare Foshou yam and honey nutritional can by combining Foshou yam with honey through screening,pre-cooking,filling,exhausting,cooling and other technical processes.The optimum technology parameter of Foshou yam and honey nutritional can was studied through single factor tests and response surface optimization.[Results]The optimum technical parameters of Foshou yam and honey nutritional can were citric acid concentration 0.1%,amount of edible salt 0.1%,cooking time 14 min and honey concentration 26%.Under these conditions,the final sensory score was 90.20.The prepared can was not only rich in nutrition,but also had good flavor and taste.[Conclusions]This study provides reference for the development and utilization of Foshou yam and the research and development of functional food.展开更多
In this paper,we consider the time-harmonic electromagnetic scattering by a perfect conductor in a homogeneous chiral environment.For three-dimensional cylindrical structures,it can be simplified as a two–dimensional...In this paper,we consider the time-harmonic electromagnetic scattering by a perfect conductor in a homogeneous chiral environment.For three-dimensional cylindrical structures,it can be simplified as a two–dimensional model problem,which can be modeled by two scalar Helmholtz equations via coupled boundary conditions.The boundary integral equation method is used to prove the unique existence of the weak solution to this problem.Then we apply the linear sampling method to recover the scatterer from one of the far field pattern of wave fields.Some numerical examples are shown to verify the correctness and effectiveness of the proposed method.展开更多
Metal-organic frameworks(MOFs)derived magnetic carbon-based nanocomposites have drawn widespread attentions due to the well distributed nanocrystals in carbon matrix.Dynamically observing the formation process is urge...Metal-organic frameworks(MOFs)derived magnetic carbon-based nanocomposites have drawn widespread attentions due to the well distributed nanocrystals in carbon matrix.Dynamically observing the formation process is urgently needed.Herein,taking zeolitic imidazolate framework(ZIF)-67 as an example,the pyrolysis process is investigated by in-situ transmission electron microscopy(TEM)assisted with ex-situ characterizations.Co nanocrystals are evenly distributed in carbon at the initial stage of carbonization.By increasing pyrolysis temperature,the nanocrystals grow bigger and migrate to carbon surface.The carbon texture transfers from amorphous to crystalline at 600°C,and thoroughly converts at 800°C.In-situ heating TEM shows that more tiny Co nanocrystals move out from the carbon texture by increasing temperature from 700 to 800°C.At 1,000°C,some escaped tiny Co nanocrystals are volatilized and disappeared.The residual escaped Co nanocrystals catalyze the formation of carbon nanotubes(CNTs).Due to the synergistic effect between Co and carbon as well as porous structure,the nanocomposites show high-efficient microwave absorption performance,which can be tuned by pyrolysis temperature,heating rate,and mass fraction.When the mass fraction is 30 wt.%,the nanocomposites obtained at 600 or 700°C display remarkable microwave absorption with optimal reflection loss(RL)smaller than−70 dB and effective absorption band larger than 4.9 GHz.Combining the in-situ and ex-situ techniques,some key findings were observed:(1)graphitization of carbon;(2)volatilization of Co nanocrystals;(3)formation process of CNTs by Co catalyst.These findings are helpful to understand the formation of MOFs derived carbon-based composites and expand their practical applications,especially for microwave absorption.展开更多
Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite n...Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite nanoparticles with a size of <10 nm, but this phase can be eliminated after the air annealing treatment. The atom ratio of Zn/Fe and concentration of oxygen vacancies decrease as the particle size of zinc ferrite increases, causing magnetic transition from superparamagnetism to ferromagnetism. The X-ray magnetic circular dichroism spectra reveal that the spin magnetic moments of Fe^(3+)are reduced, and the orbital magnetic moments are frozen with the increasing atom ratio of Zn/Fe. Therefore,saturation magnetization decreases. The saturation magnetizations of all the zinc ferrite nanoparticles decrease after the air annealing treatment, suggesting that oxygen vacancies considerably influence the magnetic properties. The air annealing treatment can minimize the number of oxygen defects,which trigger some of the Fe^(3+)–OV–Fe^(3+)ferrimagnetic couplings to transfer into the Fe^(3+)–O^(2-)–Fe^(3+)antiferromagnetic couplings. This work provides new insights regarding the magnetic performance of spinel ferrites by tuning the stoichiometric ratio and oxygen defects.展开更多
文摘At the beginning of the 20^(th)century,German scientist Richard Semon introduced the term'engram'to describe the neural substrate implicated in the processes of memory formation and retrieval[1].The trace of the corresponding biophysical and biochemical changes in the brain responding to an external stimulus is called an engram,and understanding the physical manifestations of memory formation and recall remains a fundamental yet unresolved question[2].
基金The authors wished to acknowledge the financial support of the National Key Technology R&D Program of China(nos.2011BAE22B01 and 2011BAE22B06).
文摘The effect of hot extrusion and addition of Y element on the corrosion behavior of MgeY alloy was investigated by weight loss,immersion tests and potentiodynamic polarization measurements.The results showed that the grains became finer and uniform by increasing Y element,after extrusion.The corrosion resistance of MgeY alloy after extrusion was deteriorated with the addition of Y element and corrosion rates decreased in the following order:Mge13.78Y>Mge7.46Y>Mge5.23Y.
基金2018 Undergraduate Innovation and Entrepreneurship Training Program of Huanggang Normal University(201810514045)High-level Cultivation Project of Huanggang Normal University(201816703)。
文摘[Objectives]This study was conducted to screen best process parameters for making Foshou yam and honey can.[Methods]The Foshou yam produced from Wuxue was used as a raw material to prepare Foshou yam and honey nutritional can by combining Foshou yam with honey through screening,pre-cooking,filling,exhausting,cooling and other technical processes.The optimum technology parameter of Foshou yam and honey nutritional can was studied through single factor tests and response surface optimization.[Results]The optimum technical parameters of Foshou yam and honey nutritional can were citric acid concentration 0.1%,amount of edible salt 0.1%,cooking time 14 min and honey concentration 26%.Under these conditions,the final sensory score was 90.20.The prepared can was not only rich in nutrition,but also had good flavor and taste.[Conclusions]This study provides reference for the development and utilization of Foshou yam and the research and development of functional food.
基金Supported in part by the Research Project on Teaching Reform in Ordinary Higher Education Institutions in Hunan Province(No.HNJG-20231470)。
文摘In this paper,we consider the time-harmonic electromagnetic scattering by a perfect conductor in a homogeneous chiral environment.For three-dimensional cylindrical structures,it can be simplified as a two–dimensional model problem,which can be modeled by two scalar Helmholtz equations via coupled boundary conditions.The boundary integral equation method is used to prove the unique existence of the weak solution to this problem.Then we apply the linear sampling method to recover the scatterer from one of the far field pattern of wave fields.Some numerical examples are shown to verify the correctness and effectiveness of the proposed method.
基金the National Natural Science Foundation of China(Nos.51572218,11504293,51771085,and 51801087)the Natural Science Foundation of Shaanxi Province(No.2019JM-138)+2 种基金the Natural Science Foundation from Department of Science and Technology of Shaanxi Province(Nos.2021JQ-431,2021JM-304,and 2021JQ-427)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0946)the Key Project of Research and Development of Shaanxi Province(No.2018ZDCXL-GY-08-05).
文摘Metal-organic frameworks(MOFs)derived magnetic carbon-based nanocomposites have drawn widespread attentions due to the well distributed nanocrystals in carbon matrix.Dynamically observing the formation process is urgently needed.Herein,taking zeolitic imidazolate framework(ZIF)-67 as an example,the pyrolysis process is investigated by in-situ transmission electron microscopy(TEM)assisted with ex-situ characterizations.Co nanocrystals are evenly distributed in carbon at the initial stage of carbonization.By increasing pyrolysis temperature,the nanocrystals grow bigger and migrate to carbon surface.The carbon texture transfers from amorphous to crystalline at 600°C,and thoroughly converts at 800°C.In-situ heating TEM shows that more tiny Co nanocrystals move out from the carbon texture by increasing temperature from 700 to 800°C.At 1,000°C,some escaped tiny Co nanocrystals are volatilized and disappeared.The residual escaped Co nanocrystals catalyze the formation of carbon nanotubes(CNTs).Due to the synergistic effect between Co and carbon as well as porous structure,the nanocomposites show high-efficient microwave absorption performance,which can be tuned by pyrolysis temperature,heating rate,and mass fraction.When the mass fraction is 30 wt.%,the nanocomposites obtained at 600 or 700°C display remarkable microwave absorption with optimal reflection loss(RL)smaller than−70 dB and effective absorption band larger than 4.9 GHz.Combining the in-situ and ex-situ techniques,some key findings were observed:(1)graphitization of carbon;(2)volatilization of Co nanocrystals;(3)formation process of CNTs by Co catalyst.These findings are helpful to understand the formation of MOFs derived carbon-based composites and expand their practical applications,especially for microwave absorption.
基金financially supported by the National Natural Science Foundation of China (51572218,11504293 and 11904275)the Natural Science Foundation of Shaanxi Province (2019JM-138)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department (18JK0786,19JK0413 and 20JK0946)the Key Project of Research and Development of Shaanxi Province (2018ZDCXL-GY-08-05)。
文摘Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite nanoparticles with a size of <10 nm, but this phase can be eliminated after the air annealing treatment. The atom ratio of Zn/Fe and concentration of oxygen vacancies decrease as the particle size of zinc ferrite increases, causing magnetic transition from superparamagnetism to ferromagnetism. The X-ray magnetic circular dichroism spectra reveal that the spin magnetic moments of Fe^(3+)are reduced, and the orbital magnetic moments are frozen with the increasing atom ratio of Zn/Fe. Therefore,saturation magnetization decreases. The saturation magnetizations of all the zinc ferrite nanoparticles decrease after the air annealing treatment, suggesting that oxygen vacancies considerably influence the magnetic properties. The air annealing treatment can minimize the number of oxygen defects,which trigger some of the Fe^(3+)–OV–Fe^(3+)ferrimagnetic couplings to transfer into the Fe^(3+)–O^(2-)–Fe^(3+)antiferromagnetic couplings. This work provides new insights regarding the magnetic performance of spinel ferrites by tuning the stoichiometric ratio and oxygen defects.
